"They were peers. She said, 'Go be a hero, you're ready.' They believed in each other, so losing that confidante, that support, that love was devastating to her."

The star added: "I feel like, for the first time, especially since we've started the show, she really felt like she had it balanced — she had a happy life with her partner, she had work going for her and was working her way up in the premiere, and she was loving being Supergirl and saving the world, so a giant part of her identity was wrenched from her."